Re-pointing where DPC slate used to be (pictures included!)

[Reginalddean]

Hi,

In the spring I intend to repoint all around my house, the main problem areas are where the patio used to be above the slate DPC, when I lowered the ground levels the pointing has been worn away through many years of being underground!

I intend to repoint and then paint or bitumen the first three or four courses.

My question is....Is it ok for me to repoint where the slate DPC has comeaway? If I do am I introducing a bridge for moisture to jump accross? Should I just paint over those gaps and hope the paint acts like a filler!

I have attached a couple of photos for you to see what I mean. All advice welcome.

http://picasaweb.google.com/DeanHain/PointingAndDPC

Thanks

 

[The-brickie]

Get a water proofer and mix in the mortar, 4:1 sand cement and point away!

Are you covering the brickwork up again? if not then just clean, re-point and leave to dry out, I hate covering brickwork working on the assumption that it should breathe, if it gets wet let the air dry it out.

If painted or bitumen'd and damp comes up from below ground it cant dry out above ground because its trapped behind the covering.

All IMHO of course

 

[JohnD]

yes, you are creating a damp bridge if you point over he slate. Certainly repoint the courses below and above slate level, then brush away the old mortar round the slate. and see what you are left with.

I tried a very fidddly method of repointing with a tuck to leave the edge of the slate exposed, and painting it with black Synthaprufe, but there must be a better way.

 

[Reginalddean]

Thanks for the quick responses, I like the idea of adding waterproofer to the mortar, is this ok?

Another reason I intend to paint or bitumen is to cover up the bad brickwork staining, some areas are very stained since being underground, I have tried pressure washing but it doesn't come off.

Is there any masonary paint that would allow the bricks to breath ?

Thanks again

 

[Reginalddean]

Hi, I have been doing some web research pn waterproofer for pointing but cant find anything to confirm it is ok to use on the DPC level,

Does anyone know any reason why I shouldnt use this to patch the DPC level?

Many thanks

 

[Softus]

IMHO, in order of importance, the following things matter:

1. Integrity and absorbancy of brick surface.
2. Proximity of ground.
3. DPC.

If the bricks' surface is damaged, and they get wet, and the water freezes, then you'll have a significantly bigger problem. Making the joint good and impervious to water ingress is the top priority.

If the outside ground level is too high, and/or too hard, then rain may bounce off and soak the brickwork, risking the above scenario and risking penetrating damp. Lowering the ground, and/or creating a French drain, would mitigate these risks.

If you address the above issues then exactly how much slate you have left in your sandwich is not really very important. Some people will tell you that without a full width of slate you expose the wall to rising damp problems. If you want my opinion on the subject of rising damp (and many don't), I can suggest some more in-depth reading on the subject, but the bottom line is that the times it can occur are:

a) In bricks and mortar that have become so damaged that they absorb more than their normal amount of moisture.

b) Where the ground, or internal flooring, is too high AND abuts the wall in such a way as to provide a path for moisture by capillary action.